High consistency thickener for paper pulp



Jan. 20, 1970 A. J. HAUG 3,490,361

HIGH CONSISTENCY THICKENER FOR PAPER PULP Filed Feb. 7, 1966 3 Sheets-Sheet 1 am "a INVENTOR, ANTON J. HAUG, DECEASED, MARIE J. OYLE, BY 4 I Jan. 20,. 1970 A J. HAUG HIGH CONSISTENCY THICKENER FOR PAPER PULP 3 Sheets-Sheet 2 Filed Feb. 7, 1966 R, x OD]. mEm w u .A N\C. C 1 E Rx 0 G F. MM D N A M 4 G l F Jan. 20, 1970 A. J. HAUG 3,490,361

HIGH CONSISTENCY THICKENER FOR PAPER PULP Filed Feb. 7, 1966 3 Sheets-Sheet 5 I. /2 Ill" 28 I w so 32 32' 34 I7 I 52 22 /8 A9 ll 1; I. 62

United States Patent US. Cl. 100-37 Claims This invention relates to a method and apparatus for dewatering pulp or pulp like material and more particularly to handling and removing liquid from pulp like material which is in the range of ten to fifteen percent solids or higher.

There are many known dewatering apparatus which have enjoyed varying degrees of success. One type employs a foraminous cylindrical core rotatably mounted on a generally horizontal axis. Material to be dewatered is caused to move longitudinally within the foraminous core and the excess liquid is permitted to drain through the perforations in the cylinder. Generally these machines rotate relatively slowly and consequently a relatively long core is required to handle commercially adequate quantities of material. Further, the consistency of the dewatered stock has been limited by gravity, i.e., gravity has generally been employed to separate the liquid from the material. Various means have been used to augment the separation such as by creating a suction on the outer periphery of the foraminous member, however the gain in consistency is still too limited.

Consistency of the material has been increased (more liquid has been removed) by using press rolls in the egress end of the core to squeeze out some liquid. This has been found to be very useful however the quantity of material handled has been limited by the rotation of the device.

In US. Patent 3,114,309 there is disclosed an apparatus, a centrifugal thickener, which is highly effective in removing excess liquid from material while using a minimal amount of space. This is accomplished by rotating a foraminous screen drum at a rate sufiicient to create centrifugal forces which aid in separating the liquid from the material in conjunction with press and stripping rolls. This apparatus is especially useful for removing liquid from dilute paper stock from a low of one to two percent up to a consistency range from 10 to percent and in some cases to twenty to thirty percent consistency range. Paper stock at such a low consistency range usually contains very fine fibre fragments and slimy or gelatinous material which tend to clog the small drain apertures used in conventional drums. This clogging has been avoided by use of the particular novel press and stripping rolls used in the rapidly rotating foraminous drum.

Once the consistency has been brought up to the range indicated in the above-referred-to patent it is sometimes desirable to increase the consistency even higher. Once the consistency has been increased as in the above-referred-to centrifugal thickener the stock does not have the same slimy or gelatinous characteristic and hence prob lems of processing the stock differ, e.g., the clogging problem is of a different nature due to the different physical characteristics referred to supra.

It is therefore an object of this invention to provide an apparatus and a method for removing liquid from pulp 3,490,361 Patented Jan. 20, 1970 like material such as paper stock which has a beginning consistency range in excess of approximately ten percent.

It is another object to provide an apparatus which can be used either separately or as an attachment to other stock thickening devices, in particular the centrifugal thickener disclosed in US. Patent 3,114,309.

Yet another object is the provision of an economical reliable stock thickening machine which is particularly useful in the higher stock consistency ranges.

Other objects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, steps and sequence of steps, features of construction and manipulation, and arrangements of parts, all of which will be exemplified in the structures and methods hereinafter described, and the scope of the application of which will be indicated in the following claims.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

In the accompanying drawings, in which one of the various possible embodiments of the invention is illustrated:

FIG. 1 is a cross section of an exemplary embodiment of the present invention shown in operative relation to a centrifugal paper pulp thickener, partly broken away taken on line 11 of FIGURE 2;

FIG. 2 is an end view of the high consistency thickener of the instant invention;

FIG. 3 is a top view of the thickener, with the top portion removed and parts broken away for clarity; and

FIG. 4 is a perspective view of the spider member used in the apparatus of invention.

The thickener of the instant invention is indicated generally by numeral 10 and is shown attached to a centrifugal thickener 6 of the type disclosed in United States Patent No. 3,114,309 referred to supra. Only a portion of thickener 6 is shown, since it does not constitute the invention per se. Further details of construction can be gleaned from the above-referred-to patent. It will be understood that thickener 10 can be used either independently or with any other thickener, the only criteria is that the consistency of the stock is high enough to be devoid of slimy or gelatinous material, and usually in the range of ten to thirty percent consistency range.

In the illustrated embodiment thickener 10 is shown mounted on casing 8 of the centrifugal thickener 6 by any conventional fastening means.

The pulp material to be thickened is fed into thickener 10 by a conventional screw conveyor 12. A spider 16 is attached to shaft 14 of conveyor 12 by conventional fastening means, such as the threaded fastener 15. A foraminous or pervious drum 18 is attached to the outer periphery of spider 16. Drum 18 is shown generally cylindrical however it is within the purview of the invention to employ a conical drum. A ring 20 is attached to the distal or free end of drum 18. A casing member 22 encloses thickener 10 and is divided into a white water outlet 24 and a pulp outlet 26.

Spider 16 supports drum 18 and additionally serves as an entrance for the pulp to be thickened. FIGURE 4 shows spider 16 which is formed of an axially extending hub 28, drum seating ring 30 and ribs 32 joining hub 28 and ring 30 and which effectively divides the spider into a stock inlet area and a stock directing area. Ribs 32 are shaped such that they permit pulp to enter within drum 18 without clogging and further permit employing stock directing means, plow 34, which cooperates with flight 13 of conveyor 12 to keep the stock moving into the machine and prevent any build up of material. As seen best in FIGURES 1 and 4 flight 13 ends approximately half Way between two ribs 32. This has been found to result in optimum stock movement. Material which is pushed into spider 16 is forced against the inside periphery of ring 30 by gravity and centrifugal force. As spider 16 rotates in the direction of the darts shown in FIGURE 4 the material impinges against plow 34 and is directed into the drum cavity 19. Retainer plate 17 fixed spider 16 on the end of shaft 14. The material, as will be more fully described infra, is directed along the length of drum 18 toward stock outlet 26. White water which is removed from the pulp goes through the perforations in the foraminous wall of drum 18 and thence through outlet 24. A conventional seal is formed between ring 20 and rib 40 of casing 22. Annular flanges 36, 38 form therebetween a groove 37 within which rib 40 extends thereby effectively segregating outlet 24 from outlet 26.

The stock thickening members which cooperate with foraminous drum 18 to force effiuent out of the pulp material comprise press roll 42, scraper 52, and conveyor 62. Press roll 42 is arranged to be resiliently forced against the inner drum surface and may be provided with a suit able material such as a Micarta or hard rubber covering with small axial or helical grooves 43 formed therein. Roll 42 is rotatably mounted on shaft 44 and positioned by locating blocks 45, 46. It will be noted that plow 34 is conveniently mounted by conventional means on block 46. Shaft 44 is mounted in arm 47 which is pivotably mounted on plate 48 at 49. A conventional mass 50 is placed on arm 51 fixed to pivot arm 47 to resiliently bias roll 42 against the inner periphery of drum 18.

The rotation of drum 18 will cause roll 42 to rotate and squeeze the material into a mat which then passes there between. The eflluent which is squeezed out of the mate rial is forced by centrifugal force through the perforations in drum 18. Since the material is already of a high enough consistency that it is not slimy or gelatinous the perforations do not tend to clog. Scraper bar 52 breaks up the mat of material and keeps the drum clean and is preferably mounted slightly askew in relation to the axis of revolution so that it will tend to move the loose material in the direction of the outlet end and thereby avoids random movement of the material which would interfere with optimum stock flow. Scraper 52 is mounted on bracket 54 which is adjustably mounted on casing 22 to permit both horizontal and vertical adjustment.

Positive axial control of the stock movement is obtained through use of conveyor 62. Since space available for the conveyor is limited it is preferable to use a worm conveyor in which the fiights serve as their own support. This can best be seen in FIGURE 3. Eliminating the central shaft support member such as shaft 14 of conveyor 12 mitigates the tendency for the material to plug up.

A sheave 64 is provided to drive conveyor 62. The

travel of the stock through drum 18 can be controlled by the speed of rotation of conveyor 62 so a vari-speed drive (not shown) can be used to advantage.

After the stock is thickened, it is urged out of drum 18 by the action of conveyor 62 and is forced into outlet 26 by one or more plows 21. Outlet 26 is connected (not shown) as desired to the inlet of refining apparatus or to other stock flow means.

The consistency of the thickened stock will be dependent upon several factors such as type and freeness of the stock, rate of feed, beginning consistency, etc. Generally it is possible to achieve a consistency range up to 25 to 30 percent and in certain cases up to 40 percent.

A representative illustration is as follows. A thickener was used as an attachment to the centrifugal thickener 6 referred to supra. Drum 18 had inch round perforations and was rotated at approximately 380 r.p.m.; conveyor 62 was rotated at 570 rpm. and an effective weight of 19 pounds was exerted on roll 42. Bleached kraft having a freeness of approximately 760 Canadian was brought up to a consistency of approximately 30 percent from a beginning consistency of approximately 3 percent bone dry.

In view of the above it will be seen that the several objects of the invention are achieved and other advantageous results attained.

I claim:

1. A high consistency pulp thickener comprising:

(a) a support;

(b) a generally cylindrical foraminous drum having ingress and egress ends rotatably mounted along its longitudinal axis on the support;

(0) press roll means located within the drum and biased thereagainst;

((1) stock breaker means comprising a scraper bar located within the drum in juxtaposition to the inside periphery of the drum;

(e) axial stock directing means located within the drum in juxtaposition to the inside periphery of the drum; and

(12') means to rotate the drum about its longitudinal axis.

2. A thickener according to claim 1 in which the stock breaker means is positioned angularly in front of the press roll means in the direction of rotation of the drum and the axial stock directing means is positioned angularly in front of the stock breaker means in said direction.

3. A thickener according to claim 1 in which the press roll means includes a press roll mounting arm pivota-bly connected at an end thereof to the support and mounting a press roll at another end and a weight arm is connected to the said arm intermediate the said ends so that a force applied to the weight arm will be transmitted to the Press roll.

'4. A thickener according to claim 3 in which the press roll is provided with a plurality of generally axially extending grooves in the outer periphery of the roll.

5. A thickener according to claim 1 further including:

( g) spider means on which is mounted the ingress end of the drum, said spider comprises:

(I) a cylindrical drum seating member,

(II) a hub portion, and

(III) a plurality of curved ribs connecting the seating member and the hub portion and eifecting a division of the spider into a stock inlet area and a stock directing area thereby permitting stock to enter between the ribs from the stock inlet area to the stock directing area; and

(h) plow means adapted to fit into the stock directing area so that stock fed into the thickener impinges on the plow upon rotation of the spider and drum and is thereby directed into the drum interior.

6. A thickener according to claim 5 in which the plow is mounted on the press roll means.

7. A thickener according to claim 5 in which the spider is mounted on a feed conveyor shaft, such that the end of a conveyor flight mounted on the conveyor shaft extends into the stock inlet area of the spider intermediate two ribs thereof.

8. A thickener according to claim 1 in which the axial stock directing means includes a worm conveyor and the stock breaker means includes a scraper mounted such that its longitudinal axis is inclined relative to the axial direction of the drum.

9. The method of removing white water from paper stock devoid of slimy, gelatinous character, having a consistency in excess of approximately ten per cent comprising the steps of:

(a) rotating a foraminous member;

(-b) directing stock so that it impinges against the member;

5 6 (c) squeezing the stock into a mat against the member; References Cited (d%rc-l)I;e:1}l1 ;nlgleI1111%erthe mat and separating the stock UNITED STATES PATENTS (e) moving the stock aleng the member while in cOn- 2,4833) 9/1949 Hal-1g 100157 X tact with the member; and 3,114,309 12/1963 g 10037 (f) repeating the squeezing, breaking and moving steps 5 3,199,441 8/1965 Hang loo-157 for a sufficient number of times to efiect a desired consistency range PETER FELDMAN, Primary Examiner 10. The method of claim 9 in which the squeezing step is accomplished With a surface having a plurality of 10 grboves resiliently biased against the member With an 100121, 157; 162-232- adjustable force. 

1. A HIGH CONSISTENCY PULP THICKENER COMPRISING: (A) A SUPPORT; (B) A GENERALLY CYLINDRICAL FORAMINOUS DRUM HAVING INGRESS AND EGRESS ENDS ROTATABLY MOUNTED ALONG ITS LONGITUDINAL AXIS ON THE SUPPORTS; (C) PRESS ROLL MEANS LOCATED WITHIN THE DRUM AND BIASED THEREAGAINST; (D) STOCK BREAKER MEANS COMPRISING A SCRAPER BAR LOCATED WITHIN THE DRUM IN JUXTAPOSITION TO THE INSIDE PERIPHERY OF THE DRUM; (E) AXIAL STOCK DIRECTING MEANS LOCATED WITHIN THE DRUM IN JUXTAPOSITION TO THE INSIDE PERIPHERY OF THE DRUM; AND (F) MEANS TO ROTATE THE DRUM ABOUT ITS LONGITUDINAL AXIS. 